From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0C2FBECDFA1 for ; Mon, 24 Oct 2022 08:34:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230262AbiJXIen (ORCPT ); Mon, 24 Oct 2022 04:34:43 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51386 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229721AbiJXIei (ORCPT ); Mon, 24 Oct 2022 04:34:38 -0400 Received: from out30-44.freemail.mail.aliyun.com (out30-44.freemail.mail.aliyun.com [115.124.30.44]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2C5851A229 for ; Mon, 24 Oct 2022 01:34:34 -0700 (PDT) X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R571e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=ay29a033018046060;MF=baolin.wang@linux.alibaba.com;NM=1;PH=DS;RN=10;SR=0;TI=SMTPD_---0VSvcrBd_1666600470; Received: from localhost(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0VSvcrBd_1666600470) by smtp.aliyun-inc.com; Mon, 24 Oct 2022 16:34:31 +0800 From: Baolin Wang To: akpm@linux-foundation.org Cc: david@redhat.com, ying.huang@intel.com, ziy@nvidia.com, shy828301@gmail.com, apopple@nvidia.com, baolin.wang@linux.alibaba.com, jingshan@linux.alibaba.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH v3 1/2] mm: migrate: Fix return value if all subpages of THPs are migrated successfully Date: Mon, 24 Oct 2022 16:34:21 +0800 Message-Id: X-Mailer: git-send-email 1.8.3.1 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org During THP migration, if THPs are not migrated but they are split and all subpages are migrated successfully, migrate_pages() will still return the number of THP pages that were not migrated. This will confuse the callers of migrate_pages(). For example, the longterm pinning will failed though all pages are migrated successfully. Thus we should return 0 to indicate that all pages are migrated in this case Fixes: b5bade978e9b ("mm: migrate: fix the return value of migrate_pages()") Signed-off-by: Baolin Wang Reviewed-by: Alistair Popple Cc: --- Changes from v2: - Add Fixes tag suggested by Yang Shi and Huang, Ying. - Drop 'nr_thp_split' validation suggested by Alistair. - Add reviewed tag from Alistair. - Update the commit message suggested by Andrew. Changes from v1: - Fix the return value of migrate_pages() instead of fixing the callers' validation. --- mm/migrate.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/mm/migrate.c b/mm/migrate.c index 8e5eb6e..2eb16f8 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -1582,6 +1582,13 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page, */ list_splice(&ret_pages, from); + /* + * Return 0 in case all subpages of fail-to-migrate THPs are + * migrated successfully. + */ + if (list_empty(from)) + rc = 0; + count_vm_events(PGMIGRATE_SUCCESS, nr_succeeded); count_vm_events(PGMIGRATE_FAIL, nr_failed_pages); count_vm_events(THP_MIGRATION_SUCCESS, nr_thp_succeeded); -- 1.8.3.1